1. Field of the Invention
The present invention relates to a roll sheet holder which rotatably holds a roll sheet wound on a cylindrical sheet core and is removably mounted in a tape printer provided with a feeding device for feeding the roll sheet and a printing unit for printing on the roll sheet. Further, the present invention relates to a tape printer in which the roll sheet holder is removably mounted.
2. Description of Related Art
Heretofore, various types of tape printers have been proposed to print characters and others on a long sheet formed of a self-adhesive sheet applied with a release sheet by means of a thermal head. Some tape printers of this type are provided with a roll sheet wound on a sheet core, a roll sheet holder which rotatably holds therein the sheet core, a support mechanism which removably mounts the roll sheet holder in the tape printer, and a feeding device for feeding part of the roll sheet while drawing the roll sheet from the roll sheet holder. The roll sheet holder may be selected from among plural holders of different sizes individually corresponding to various sheet widths.
One of the roll sheet holders mounted in the tape printer is disclosed in Japanese utility model unexamined publication No. H3-19047 (1997-19407). This is a recording sheet holding case made of a heat insulating material and for storing a roll of a thermal recording sheet wound on a sheet core. This holding case is constructed of a mechanism for supporting both ends of the sheet core, a recording sheet drawing port through which part of the thermal recording sheet is unwound, and pits and projections formed on an outer surface of the case to indicate the kind of thermal recording sheet stored in the case.
For image recording, the tape printer using the recording sheet holding case constructed as above can distinguish the kind of thermal recording sheet stored in the sheet holding case by means of a microswitch or the like provided in the bottom of the sheet holding case and thereby control the application of electric power to a thermal head. Accordingly, images can be printed at an appropriate color density on the thermal recording sheet mounted in the printer.
However, the conventional tape printer in which the above mentioned recording sheet holding case is mounted has the following disadvantages. When part of the thermal recording sheet is unwound, the holding case is caused to rotate in a direction of drawing of the sheet. Accordingly, lower end faces of the projections of the holding case whereby the microswitch is pressed down are moved up to come off the microswitch. This may cause a problem that images are printed at an inappropriate color density on the thermal recording sheet.